Protons are transferred between a conjugate acid-base pair during a chemical reaction. A conjugate pair is composed of an acid and a base that have common features. These common features result in an equal loss and gain of protons between the pairs during a reaction.
An acid and a base must react for a conjugate base to form, and the proton transfer must be equal. After the reaction, the original acid gains a proton, forming a conjugate base. The original base donates a proton and becomes a conjugate acid. The conjugate base of an acid may be identified by finding the compound that differs from the acid by one proton.